Steerable segmented endoscope and method of insertion

ABSTRACT

A system for determining the shape of a surgical instrument includes an elongate instrument body having a selectively steerable distal tip, a pair of automatically controlled segments proximal to the selectively steerable distal tip, and a joint that couples the pair of adjacent automatically controlled segments together. An actuator changes an angle of the joint and a position encoder provides information associated with the joint angle. A controller receives the information associated with the angle of the joint and generates a three dimensional model of a shape of the instrument. A method for determining the three dimensional shape of an instrument includes providing axial position data to a controller, providing angular position data to the controller from a respective segment controller, and generating a three-dimensional model of a shape of said instrument using the axial position data and the angular position data.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/796,220 entitled “Steerable Segmented Endoscope and Methodof Insertion” filed Apr. 27, 2007, which is a continuation of Ser. No.10/622,801 entitled “Steerable Segmented Endoscope and Method ofInsertion” filed Jul. 18, 2003, which is a continuation of U.S. patentapplication Ser. No. 09/969,927, now U.S. Pat. No. 6,610,007 entitled“Steerable Segmented Endoscope and Method of Insertion” filed Oct. 2,2001, which is a continuation-in-part of U.S. patent application Ser.No. 09/790,204, now U.S. Pat. No. 6,468,203, entitled “SteerableEndoscope and Improved Method of Insertion” filed Feb. 20, 2001, whichclaims priority of U.S. Provisional Patent Application No. 60/194,140filed Apr. 3, 2000, each of which is incorporated herein by reference inits entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to endoscopes and endoscopicmedical procedures. More particularly, it relates to a method andapparatus to facilitate insertion of a flexible endoscope along atortuous path, such as for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

An endoscope is a medical instrument for visualizing the interior of apatient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

Colonoscopy is a medical procedure in which a flexible endoscope, orcolonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-19 mm in diameter,and includes a fiberoptic imaging bundle or a miniature camera locatedat the instrument's tip, illumination fibers, one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels. The colonoscope is inserted via thepatient's anus and is advanced through the colon, allowing direct visualexamination of the colon, the ileocecal valve and portions of theterminal ileum. Insertion of the colonoscope is complicated by the factthat the colon represents a tortuous and convoluted path. Considerablemanipulation of the colonoscope is often necessary to advance thecolonoscope through the colon, making the procedure more difficult andtime consuming and adding to the potential for complications, such asintestinal perforation. Steerable colonoscopes have been devised tofacilitate selection of the correct path though the curves of the colon.However, as the colonoscope is inserted farther and farther into thecolon, it becomes more difficult to advance the colonoscope along theselected path. At each turn, the wall of the colon must maintain thecurve in the colonoscope. The colonoscope rubs against the mucosalsurface of the colon along the outside of each turn. Friction and slackin the colonoscope build up at each turn, making it more and moredifficult to advance and withdraw the colonoscope. In addition, theforce against the wall of the colon increases with the buildup offriction. In cases of extreme tortuosity, it may become impossible toadvance the colonoscope all of the way through the colon.

Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. patents, the disclosures of which are herebyincorporated by reference in their entirety: U.S. Pat. Nos. 4,753,223;5,337,732; 5,662,587; 4,543,090; 5,383,852; 5,487,757 and 5,337,733.

SUMMARY OF THE INVENTION

In keeping with the foregoing discussion, the present invention takesthe form of a steerable endoscope for negotiating tortuous paths througha patient's body. The steerable endoscope can be used for a variety ofdifferent diagnostic and interventional procedures, includingcolonoscopy, upper endoscopy, bronchoscopy, thoracoscopy, laparoscopyand video endoscopy. The steerable endoscope is particularly well suitedfor negotiating the tortuous curves encountered when performing acolonoscopy procedure.

The steerable endoscope has an elongated body with a manually orselectively steerable distal portion and an automatically controlledproximal portion. The selectively steerable distal portion can beselectively steered or bent up to a full 180 degree bend in anydirection. A fiberoptic imaging bundle and one or more illuminationfibers extend through the body from the proximal end to the distal end.Alternatively, the endoscope can be configured as a video endoscope witha miniaturized video camera, such as a CCD camera, which transmitsimages to a video monitor by a transmission cable or by wirelesstransmission, or alternatively through the use of CMOS imagingtechnology. Optionally, the endoscope may include one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels.

A proximal handle attached to the elongate body includes an ocular fordirect viewing and/or for connection to a video camera, a connection toan illumination source and one or more luer lock fittings that areconnected to the instrument channels. The handle is connected to asteering control for selectively steering or bending the selectivelysteerable distal portion in the desired direction and to an electronicmotion controller for controlling the automatically controlled proximalportion of the endoscope. An axial motion transducer is provided tomeasure the axial motion of the endoscope body as it is advanced andwithdrawn. Optionally, the endoscope may include a motor or linearactuator for both automatically advancing and withdrawing the endoscope,or for automatically advancing and passively withdrawing the endoscope.

One preferable embodiment of the endoscope includes a segmentedendoscopic embodiment having multiple independently controllablesegments which may be individually motorized and interconnected byjoints. Each of the individual adjacent segments may be pivotable abouttwo independent axes to offer a range of motion during endoscopeinsertion into a patient.

This particular embodiment, as mentioned, may have individual motors,e.g., small brushed DC motors, to actuate each individual segment.Furthermore, each segment preferably has a backbone segment whichdefines a lumen therethrough to allow a continuous lumen to pass throughthe entire endoscopic instrument to provide an access channel throughwhich wires, optical fibers, air and/or water channels, variousendoscopic tools, or any variety of devices and wires may be routed. Theentire assembly, i.e., motors, backbone, cables, etc., may be encased orcovered in a biocompatible material, e.g., a polymer, which is alsopreferably lubricious to allow for minimal frictional resistance duringendoscope insertion and advancement into a patient. This biocompatiblecover may be removable from the endoscopic body to expose the motors andbackbone assembly to allow for direct access to the components. This mayalso allow for the cover to be easily replaced and disposed after use ina patient.

The method of the present invention involves inserting the distal end ofthe endoscope body into a patient, either through a natural orifice orthrough an incision, and steering the selectively steerable distalportion to select a desired path. When the endoscope body is advanced orinserted further into the patient's body, the electronic motioncontroller operates the automatically controlled proximal portion of thebody to assume the selected curve of the selectively steerable distalportion. This process is repeated by selecting another desired path withthe selectively steerable distal portion and advancing the endoscopebody again. As the endoscope body is further advanced, the selectedcurves propagate proximally along the endoscope body. Similarly, whenthe endoscope body is withdrawn proximally, the selected curvespropagate distally along the endoscope body, either automatically orpassively. This creates a sort of serpentine motion in the endoscopebody that allows it to negotiate tortuous curves along a desired paththrough or around and between organs within the body.

The method can be used for performing colonoscopy or other endoscopicprocedures, such as bronchoscopy, thoracoscopy, laparoscopy and videoendoscopy. In addition, the apparatus and methods of the presentinvention can be used for inserting other types of instruments, such assurgical instruments, catheters or introducers, along a desired pathwithin the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art colonoscope being employed for a colonoscopicexamination of a patient's colon.

FIG. 2 shows a first embodiment of the steerable endoscope of thepresent invention.

FIG. 3 shows a second embodiment of the steerable endoscope of thepresent invention.

FIG. 4 shows a third embodiment of the steerable endoscope of thepresent invention.

FIG. 5 shows a fourth embodiment of the steerable endoscope of thepresent invention.

FIG. 6 shows a wire frame model of a section of the body of theendoscope in a neutral or straight position.

FIG. 7 shows the wire frame model of the endoscope body shown in FIG. 6passing through a curve in a patient's colon.

FIG. 8 shows a representative portion of an alternative endoscopic bodyembodiment having multiple segments interconnected by joints.

FIG. 9 shows a partial schematic representation of the embodiment ofFIG. 8 showing two segments being pivotable about two independent axes.

FIG. 10 shows a preferable endoscope embodiment having motorizedsegmented joints.

FIGS. 11A-11B show exploded isometric assembly views of two adjacentsegments and an individual segment, respectively, from the embodimentshown in FIG. 10.

FIGS. 12-17 show the endoscope of the present invention being employedfor a colonoscopic examination of a patient's colon.

FIGS. 18-20 show an endoscope being advanced through a patient's colonwhile a datum measures the distance advanced into the patient.

FIG. 21 shows a schematic representation of one embodiment of a controlsystem which may be used to control and command the individual segmentsof a segmented endoscopic device of the type shown in FIGS. 8-11B.

FIG. 22 shows a flow chart embodiment for the master controlleralgorithm which may be used to control the overall function duringendoscope insertion into a patient.

FIG. 23 shows a flowchart embodiment of the segment controlleralgorithm.

FIGS. 24-26 shows a non-contact method of measurement and tracking of anendoscope using an external navigational system such as a globalpositioning system.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a prior art colonoscope 500 being employed for acolonoscopic examination of a patient's colon C. The colonoscope 500 hasa proximal handle 506 and an elongate body 502 with a steerable distalportion 504. The body 502 of the colonoscope 500 has been lubricated andinserted into the colon C via the patient's anus A. Utilizing thesteerable distal portion 504 for guidance, the body 502 of thecolonoscope 500 has been maneuvered through several turns in thepatient's colon C to the ascending colon G. Typically, this involves aconsiderable amount of manipulation by pushing, pulling and rotating thecolonoscope 500 from the proximal end to advance it through the turns ofthe colon C. After the steerable distal portion 504 has passed, the wallof the colon C maintains the curve in the flexible body 502 of thecolonoscope 500 as it is advanced. Friction develops along the body 502of the colonoscope 500 as it is inserted, particularly at each turn inthe colon C. Because of the friction, when the user attempts to advancethe colonoscope 500, the body 502′ tends to move outward at each curve,pushing against the wall of the colon C, which exacerbates in theproblem by increasing the friction and making it more difficult toadvance the colonoscope 500. On the other hand, when the colonoscope 500is withdrawn, the body 502″ tends to move inward at each curve taking upthe slack that developed when the colonoscope 500 was advanced. When thepatient's colon C is extremely tortuous, the distal end of the body 502becomes unresponsive to the user's manipulations, and eventually it maybecome impossible to advance the colonoscope 500 any farther. Inaddition to the difficulty that it presents to the user, tortuosity ofthe patient's colon also increases the risk of complications, such asintestinal perforation.

FIG. 2 shows a first embodiment of the steerable endoscope 100 of thepresent invention. The endoscope 100 has an elongate body 102 with amanually or selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The selectively steerabledistal portion 104 can be selectively steered or bent up to a full 180degree bend in any direction. A fiberoptic imaging bundle 112 and one ormore illumination fibers 114 extend through the body 102 from theproximal end 110 to the distal end 108. Alternatively, the endoscope 100can be configured as a video endoscope with a miniaturized video camera,such as a CCD camera, positioned at the distal end 108 of the endoscopebody 102. The images from the video camera can be transmitted to a videomonitor by a transmission cable or by wireless transmission where imagesmay be viewed in real-time or recorded by a recording device onto analogrecording medium, e.g., magnetic tape, or digital recording medium,e.g., compact disc, digital tape, etc. Optionally, the body 102 of theendoscope 100 may include one or two instrument channels 116, 118 thatmay also be used for insufflation or irrigation, air and water channels,and vacuum channels. The body 102 of the endoscope 100 is highlyflexible so that it is able to bend around small diameter curves withoutbuckling or kinking while maintaining the various channels intact. Whenconfigured for use as a colonoscope, the body 102 of the endoscope 100is typically from 135 to 185 cm in length and approximately 12-13 mm indiameter. The endoscope 100 can be made in a variety of other sizes andconfigurations for other medical and industrial applications.

A proximal handle 120 is attached to the proximal end 110 of theelongate body 102. The handle 120 includes an ocular 124 connected tothe fiberoptic imaging bundle 112 for direct viewing and/or forconnection to a video camera 126 or a recording device 127. The handle120 is connected to an illumination source 128 by an illumination cable134 that is connected to or continuous with the illumination fibers 114.A first luer lock fitting, 130 and a second luer lock fitting 132 on thehandle 120 are connected to the instrument channels 116, 118.

The handle 120 is connected to an electronic motion controller 140 byway of a controller cable 136. A steering control 122 is connected tothe electronic motion controller 140 by way of a second cable 13 M. Thesteering control 122 allows the user to selectively steer or bend theselectively steerable distal portion 104 of the body 102 in the desireddirection. The steering control 122 may be a joystick controller asshown, or other known steering control mechanism. The electronic motioncontroller 140 controls the motion of the automatically controlledproximal portion 106 of the body 102. The electronic motion controller140 may be implemented using a motion control program running on amicrocomputer or using an application-specific motion controller.Alternatively, the electronic motion controller 140 may be implementedusing, a neural network controller.

An axial motion transducer 150 is provided to measure the axial motionof the endoscope body 102 as it is advanced and withdrawn. The axialmotion transducer 150 can be made in many possible configurations. Byway of example, the axial motion transducer 150 in FIG. 2 is configuredas a ring 152 that surrounds the body 102 of the endoscope 100. Theaxial motion transducer 150 is attached to a fixed point of reference,such as the surgical table or the insertion point for the endoscope 100on the patient's body. As the body 102 of the endoscope 100 slidesthrough the axial motion transducer 150, it produces a signal indicativeof the axial position of the endoscope body 102 with respect to thefixed point of reference and sends a signal to the electronic motioncontroller 140 by telemetry or by a cable (not shown). The axial motiontransducer 150 may use optical, electronic or mechanical means tomeasure the axial position of the endoscope body 102. Other possibleconfigurations for the axial motion transducer 150 are described below.

FIG. 3 shows a second embodiment of the endoscope 100 of the presentinvention. As in the embodiment of FIG. 2, the endoscope 100 has anelongate body 102 with a selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The steering control 122is integrated into proximal handle 120 in the form or one or two dialsfor selectively steering, the selectively steerable distal portion 104of the endoscope 100. Optionally, the electronic motion controller 140may be miniaturized and integrated into proximal handle 120, as well. Inthis embodiment, the axial motion transducer 150 is configured with abase 154 that is attachable to a fixed point of reference, such as thesurgical table. A first roller 156 and a second roller 158 contact theexterior of the endoscope body 102. A multi-turn potentiometer 160 orother motion transducer is connected to the first roller 156 to measurethe axial motion of the endoscope body 102 and to produce a signalindicative of the axial position.

The endoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the axial motion transducer 150.Alternatively, the first roller 156 and/or second roller 158 may beconnected to at least one motor, e.g., motor 162, for automaticallyadvancing and withdrawing the body 102 of the endoscope 100.

FIG. 4 shows a third embodiment of the endoscope 100 of the presentinvention, which utilizes an elongated housing 170 to organize andcontain the endoscope 100. The housing 170 has a base 172 with a lineartrack 174 to guide the body 102 of the endoscope 100. The housing 170may have an axial motion transducer 150′ that is configured as a linearmotion transducer integrated into the linear track 174. Alternatively,the housing, 170 may have an axial motion transducer 150″ configuredsimilarly to the axial motion transducer 150 in FIG. 2 or 3. Theendoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 170. Alternatively, thehousing 170 may include a motor 176 or other linear motion actuator forautomatically advancing and withdrawing the body 102 of the endoscope100. In another alternative configuration, a motor with friction wheels,similar to that described above in connection with FIG. 3, may beintegrated into the axial motion transducer 150″.

FIG. 5 shows a fourth embodiment of the endoscope 100 of the presentinvention, which utilizes a rotary housing 180 to organize and containthe endoscope 100. The housing 180 has a base 182 with a rotating drum184 to guide the body 102 of the endoscope 100. The housing 180 may havean axial motion transducer 150′″ that is configured as a potentiometerconnected to the pivot axis 186 of the rotating drum 184. Alternatively,the housing 180 may have an axial motion transducer 150″ configuredsimilarly to the axial motion transducer 150 in FIG. 2 or 3. Theendoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 180. Alternatively, thehousing 180 may include a motor 188 connected to the rotating drum 184for automatically advancing and withdrawing the body 102 of theendoscope 100. In another alternative configuration, a motor withfriction wheels, similar to that described above in connection with FIG.3, may be integrated into the axial motion transducer 150″.

FIG. 6 shows a wire frame model of a section of the body 102 of theendoscope 100 in a neutral or straight position. Most of the internalstructure of the endoscope body 102 has been eliminated in this drawingfor the sake of clarity. The endoscope body 102 is divided up intosections 1, 2, 3 . . . 10, etc. The geometry of each section is definedby four length measurements along the a, b, c and d axes. For example,the geometry of section 1 is defined by the four length measurementsl_(1a), l_(1b), l_(1c), l_(1d), and the geometry of section 2 is definedby the four length measurements l_(2a), l_(2b), l_(2c), l_(2d), etc.Preferably, each of the length measurements is individually controlledby a linear actuator (not shown). The linear actuators may utilize oneof several different operating principles. For example, each of thelinear actuators may be a self-heating NiTi alloy linear actuator or anelectrorheological plastic actuator, or other known mechanical,pneumatic, hydraulic or electromechanical actuator. The geometry of eachsection may be altered using the linear actuators to change the fourlength measurements along the a, b, c and d axes. Preferably, the lengthmeasurements are changed in complementary pairs to selectively bend theendoscope body 102 in a desired direction. For example, to bend theendoscope body 102 in the direction of the a axis, the measurementsl_(1a), l_(2a), l_(3a) . . . l_(10a) would be shortened and themeasurements l_(1b), l_(2b), l_(3b) . . . l_(10b) would be lengthened anequal amount. The amount by which these measurements are changeddetermines the radius of the resultant curve.

In the selectively steerable distal portion 104 of the endoscope body102, the linear actuators that control the a, b, c and d axismeasurements of each section are selectively controlled by the userthrough the steering control 122. Thus, by appropriate control of the a,b, c and d axis measurements, the selectively steerable distal portion104 of the endoscope body 102 can be selectively steered or bent up to afull 180 degrees in any direction.

In the automatically controlled proximal portion 106, however, the a, b,c and d direction measurements of each section are automaticallycontrolled by the electronic motion controller 140, which uses a curvepropagation method to control the shape of the endoscope body 102. Toexplain how the curve propagation method operates, FIG. 7 shows the wireframe model of a part of the automatically controlled proximal portion106 of the endoscope body 102 shown in FIG. 6 passing, through a curvein a patient's colon C. For simplicity, an example of a two-dimensionalcurve is shown and only the a and b axes will be considered. In athree-dimensional curve all four of the a, b, c and d axes would bebrought into play.

In FIG. 7, the endoscope body 102 has been maneuvered through the curvein the colon C with the benefit of the selectively steerable distalportion 104 (this part of the procedure is explained in more detailbelow) and now the automatically controlled proximal portion 106 residesin the curve. Sections 1 and 2 are in a relatively straight part of thecolon C, therefore l_(1a)=l_(1b) and l_(2a)=l_(2b). However, becausesections 3-7 are in the S-shaped curved section, l_(3a)<l_(3b),l_(4a)<l_(4b) and l_(5a)<l_(5b), but l_(6a)>l_(6b), l_(7a)<l_(7b) andl_(8a)>l_(8b). When the endoscope body 102 is advanced distally by oneunit, section 1 moves into the position marked 1′, section 2 moves intothe position previously occupied by section 1, section 3 moves into theposition previously occupied by section 2, etc. The axial motiontransducer 150 produces a signal indicative of the axial position of theendoscope body 102 with respect to a fixed point of reference and sendsthe signal to the electronic motion controller 140, under control of theelectronic motion controller 140, each time the endoscope body 102advances one unit, each section in the automatically controlled proximalportion 106 is signaled to assume the shape of the section thatpreviously occupied the space that it is now in. Therefore, when theendoscope body 102 is advanced to the position marked 1′, l_(1a)=l_(1b),l_(2a)=l_(2b), l_(3a)=l_(3b), l_(4a)<l_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)>l_(7b) and l_(8a)>l_(8b), and l_(9a)>l_(9b), whenthe endoscope body 102 is advanced to the position marked 1″,l_(1a)=l_(1b), l_(2a)=l₂, l_(3a)=l_(3b), l_(4a)=l_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)<l_(7b), l_(8a)>l_(8b), l_(9a)>l_(9b), andl_(10a)>l_(10b). Thus, the S-shaped curve propagates proximally alongthe length of the automatically controlled proximal portion 106 of theendoscope body 102. The S-shaped curve appears to be fixed in space, asthe endoscope body 102 advances distally.

Similarly, when the endoscope body 102 is withdrawn proximally, eachtime the endoscope body 102 is moved proximally by one unit, eachsection in the automatically controlled proximal portion 106 is signaledto assume the shape of the section that previously occupied the spacethat it is now in. The S-shaped curve propagates distally along thelength of the automatically controlled proximal portion 106 of theendoscope body 102, and the S-shaped curve appears to be fixed in space,as the endoscope body 102 withdraws proximally.

Whenever the endoscope body 102 is advanced or withdrawn, the axialmotion transducer 150 detects the change in position and the electronicmotion controller 140 propagates the selected curves proximally ordistally along the automatically controlled proximal portion 106 of theendoscope body 102 to maintain the curves in a spatially fixed position.This allows the endoscope body 102 to move through tortuous curveswithout putting unnecessary force on the wall of the colon C.

FIG. 8 shows a representative portion of an alternative endoscopic bodyembodiment 190 which has multiple segments 192 interconnected by joints194. In this embodiment, adjacent segments 192 can be moved or angledrelative to one another by a joint 194 having at least onedegree-of-freedom, and preferably having multiple degrees-of-freedom,preferably about two axes as shown here. As seen further in FIG. 9, apartial schematic representation 196 of the embodiment 190 is shownwhere two segments 192 may be rotated about joint 194 about the twoindependent axes. The range of motion may be described in relation tospherical axes 198 by angles α and β.

As mentioned above, such a segmented body may be actuated by a varietyof methods. A preferable method involves the use of electromechanicalmotors individually mounted on each individual segment to move thesegments relative to one another. FIG. 10 shows a preferable embodiment200 having motorized segmented joints. Each segment 192 is preferablycomprised of a backbone segment 202, which also preferably defines atleast one lumen running through it to provide an access channel throughwhich wires, optical fibers, air and/or water channels, variousendoscopic tools, or any variety of devices and wires may be routedthrough. The backbone segment may be made of a variety of materialswhich are preferably biocompatible and which provide sufficient strengthto support the various tools and other components, e.g., stainlesssteel. Although much of the description is to an individual segment 192,each of the segments 192 are preferably identical, except for thesegment (or first few segments) located at the distal tip, and thefollowing description readily applies to at least a majority of thesegments 192.

A single motor, or multiple motors depending upon the desired result andapplication, may be attached to at least a majority of the segments. Anembodiment having a single motor on a segment is illustrated in FIG. 10where an individual motor 204 is preferably attached to backbone 202 andis sufficiently small and compact enough so as to present a relativelysmall diameter which is comfortable and small enough for insertion intoa patient without trauma. Motor 204, which is shown here as being asmall brushed DC motor, may be used for actuating adjacent segments 192and may be controlled independently from other motors. Various motors,aside from small brushed DC motors, may also be used such as AC motors,linear motors, etc. Each motor 204 also preferably contains within thehousing not only the electromechanical motor assembly EM itself, butalso a gear reduction stage GR, and a position encoder PE. A gearreduction stage GR attached to the motor assembly EM will allow for theuse of the motor 204 in its optimal speed and torque range by changinghigh-speed, low-torque operating conditions into a more usefullow-speed, high-torque output. The position encoder PE may be aconventional encoder to allow the controlling computer to read theposition of the segment's joint 194 by keeping track of the angularrotational movement of the output shaft of the motor 204.

Each motor 204 has a rotatable shaft which extends from an end of themotor 204 to provide for the transmission of power to actuate thesegments 192. Upon this shaft, a spool 206 may be rotatingly attachedwith a first end of the cable 208 further wound about the spool 206. Thecable 208 may then be routed from spool 206 through a channel 212 whichis defined in the cable guide 210 and out through opening 214 (as seenin greater detail in FIGS. 11A-11B) to cable anchor 216, to which thesecond end of the cable 208 is preferably attached, e.g., by crimpingand/or soldering. The cable guide 210 serves to capture the cable 208that is wound about the spool 206. The cable anchor 216 is attachedacross a universal joint pivot 220 to an adjacent segment 192 via a pin218 and may be shaped like a conventional electronic ring connectorhaving a round section defining a hole therethrough for mounting to thesegment 192 and an extension protruding from the anchor 216 forattaching the second end of the cable 208. Cable 208 may comprise a widevariety of filaments, strands, wires, chains, braids, etc. any of whichmay be made of a wide variety of biocompatible materials, e.g., metalssuch as stainless steel, polymers such as plastics and Nylon, etc.

In operation, when the motor 204 is operated to spin the shaft in afirst direction, e.g., clockwise, the spool 206 rotates accordingly andthe cable 208 pulls in a corresponding direction on the adjacent segment192 and transmits the torque to subsequently actuate it along a firstaxis. When the motor 204 is operated to spin the shaft in a seconddirection opposite to the first, e.g., counter-clockwise, the spool 206again rotates accordingly and the cable 208 would then pull in thecorresponding opposing direction on the adjacent segment 192 tosubsequently transmit the torque and actuate it in the oppositedirection.

FIGS. 11A and 11B show exploded isometric assembly views of two adjacentsegments and an individual segment, respectively, from the embodimentshown in FIG. 10. As seen in FIG. 11A, backbone 202 is seen with thelumen 221, which may be used to provide a working channel, as describedabove. Also seen are channel 212 defined in cable guide 210 as well asopening 214 for the cable 208 to run through. In interconnectingadjacent segments and to provide the requisite degree-of-freedom betweensegments, a preferable method of joining involves using the universaljoint pivot 220. However, other embodiments, rather than using auniversal joint pivot 220, may use a variety of joining methods, e.g., aflexible tube used to join two segments at their respective centers, aseries of single degree-of-freedom joints that may be closely spaced,etc. This particular embodiment describes the use of the universal jointpivot 220. At the ends of backbone 202 adjacent to other segments, apair of universal yoke members 224 may be formed with a pair ofcorresponding pin openings 226. As the universal joint pivot 220 isconnected to a first pair of yoke members 224 on one segment, acorresponding pair of yoke members 224 from the adjacent segment mayalso be attached to the joint pivot 220.

As seen further in FIG. 11B, the universal joint pivot 220 is shown inthis embodiment as a cylindrical ring having two sets of opposingreceiving holes 228 for pivotally receiving corresponding yoke members224. The receiving holes 228 are shown as being spaced apart at 90°intervals, however, in other variations, receiving holes may be spacedapart at other angles depending upon the desired degree-of-freedom andapplication. Also seen is an exploded assembly of spool 206 removed frommotor 204 exposing drive shaft 205. With motor 204 displaced frombackbone 202, the groove 230 is revealed as formed in the backbone 202.This groove 230 may be depressed in backbone 202 to preferably match theradius of the motor 204 housing not only to help locate the motor 204adjacent to backbone 202, but also to help in reducing the overalldiameter of the assembled segment. The motor 204 may be attached to thebackbone 202 by various methods, e.g., adhesives, clamps, bands,mechanical fasteners, etc. A notched portion 232 may also be formed inthe cable guide 210 as shown to help in further reducing segmentdiameter.

Prior to insertion into a patient, the endoscope 200 may be wound ontothe rotating drum 184 within the rotary housing 180 of FIG. 5 forstorage and during use, where it may optionally be configured to have adiagnostic check performed automatically. When the endoscope 200 iswound onto the drum 184, adjacent segments 192 will have a predeterminedangle relative to one another, as determined initially by the diameterof the drum 184 and the initial configuration of the storage unit inwhich the endoscope 200 may be positioned. During a diagnostic checkbefore insertion, a computer may be configured to automatically sense ormeasure the angles between each adjacent segments 192. If any of theadjacent segments 192 indicate a relative measured angle out of apredetermined acceptable range of angles, this may indicate a segment192 being out of position and may indicate a potential point of problemsduring endoscope 200 use. Accordingly, the computer may subsequentlysound an audible or visual alarm and may also place each of the segments192 into a neutral position to automatically prevent further use or toprevent any trauma to the patient.

FIGS. 12-17 show the endoscope 100 of the present invention beingemployed for a colonoscopic examination of a patient's colon. In FIG.12, the endoscope body 102 has been lubricated and inserted into thepatient's colon C through the anus A. The distal end 108 of theendoscope body 102 is advanced through the rectum R until the first turnin the colon C is reached, as observed through the ocular 124 or on avideo monitor. To negotiate the turn, the selectively steerable distalportion 104 of the endoscope body 102 is manually steered toward thesigmoid colon S by the user through the steering control 122. Thecontrol signals from the steering control 122 to the selectivelysteerable distal portion 104 are monitored by the electronic motioncontroller 140. When the correct curve of the selectively steerabledistal portion 104 for advancing the distal end 108 of the endoscopebody 102 into the sigmoid colon S has been selected, the curve is loggedinto the memory of the electronic motion controller 140 as a reference.This step can be performed in a manual mode, in which the user gives acommand to the electronic motion controller 140 to record the selectedcurve, using keyboard commands or voice commands. Alternatively, thisstep can be performed in an automatic mode, in which the user signals tothe electronic motion controller 140 that the desired curve has beenselected by advancing the endoscope body 102 distally. In this way, athree dimensional map of the colon or path may be generated andmaintained for future applications.

Whether operated in manual mode or automatic mode, once the desiredcurve has been selected with the selectively steerable distal portion104, the endoscope body 102 is advanced distally and the selected curveis propagated proximally along the automatically controlled proximalportion 106 of the endoscope body 102 by the electronic motioncontroller 140, as described above. The curve remains fixed in spacewhile the endoscope body 102 is advanced distally through the sigmoidcolon S. In a particularly tortuous colon, the selectively steerabledistal portion 104 may have to be steered through multiple curves totraverse the sigmoid colon S.

As illustrated in FIG. 13, the user may stop the endoscope 100 at anypoint for examination or treatment of the mucosal surface or any otherfeatures within the colon C. The selectively steerable distal portion104 may be steered in any direction to examine the inside of the colonC. When the user has completed the examination of the sigmoid colon S,the selectively steerable distal portion 104 is steered in a superiordirection toward the descending colon D. Once the desired curve has beenselected with the selectively steerable distal portion 104, theendoscope body 102 is advanced distally into the descending colon D, andthe second curve as well as the first curve are propagated proximallyalong the automatically controlled proximal portion 106 of the endoscopebody 102, as shown in FIG. 14.

If, at any time, the user decides that the path taken by the endoscopebody 102 needs to be revised or corrected, the endoscope 100 may bewithdrawn proximally and the electronic motion controller 140 commandedto erase the previously selected curve. This can be done manually usingkeyboard commands or voice commands or automatically by programming theelectronic motion controller 140 to go into a revise mode when theendoscope body 102 is withdrawn a certain distance. The revised orcorrected curve is selected using the selectively steerable distalportion 104, and the endoscope body 102 is advanced as described before.

The endoscope body 102 is advanced through the descending colon D untilit reaches the left (splenic) flexure F₁ of the colon. Here, in manycases, the endoscope body 102 must negotiate an almost 180 degreehairpin turn. As before, the desired curve is selected using theselectively steerable distal portion 104, and the endoscope body 102 isadvanced distally through the transverse colon T, as shown in FIG. 15.Each of the previously selected curves is propagated proximally alongthe automatically controlled proximal portion 106 of the endoscope body102. The same procedure is followed at the right (hepatic) flexure Fr ofthe colon and the distal end 108 of the endoscope body 102 is advancedthrough the ascending colon G to the cecum E, as shown in FIG. 16. Thececum E, the ileocecal valve V and the terminal portion of the ileum Ican be examined from this point using, the selectively steerable distalportion 104 of the endoscope body 102.

FIG. 17 shows the endoscope 100 being withdrawn through the colon C. Asthe endoscope 100 is withdrawn, the endoscope body 102 follows thepreviously selected curves by propagating the curves distally along theautomatically controlled proximal portion 106, as described above. Atany point, the user may stop the endoscope 100 for examination ortreatment of the mucosal surface or any other features within the colonC using the selectively steerable distal portion 104 of the endoscopebody 102. At any given time, the endoscope 100 may be withdrawn orback-driven by a desired distance.

In one preferred method according to the present invention, theelectronic motion controller 140 includes an electronic memory in whichis created a three-dimensional mathematical model of the patient's colonor other anatomy through which the endoscope body 102 is maneuvered. Thethree-dimensional model can be annotated by the operator to record thelocation of anatomical landmarks, lesions, polyps, biopsy samples andother features of interest. The three-dimensional model of the patient'sanatomy can be used to facilitate reinsertion of the endoscope body 102in subsequent procedures. In addition, the annotations can be used toquickly find the location of the features of interest. For example, thethree-dimensional model can be annotated with the location where abiopsy sample was taken during an exploratory endoscopy. The site of thebiopsy sample can be reliably located again in follow-up procedures totrack the progress of a potential disease process and/or to perform atherapeutic procedure at the site.

In one particularly preferred variation of this method, the electronicmotion controller 140 can be programmed, based on the three-dimensionalmodel in the electronic memory, so that the endoscope body 102 willautomatically assume the proper shape to follow the desired path as itis advanced through the patient's anatomy. In embodiments of thesteerable endoscope 100 that are configured for automatically advancingand withdrawing the endoscope body 102, as described above in connectionwith FIGS. 3, 4 and 5, the endoscope body 102 can be commanded toadvance automatically though the patient's anatomy to the site of apreviously noted lesion or other point of interest based on thethree-dimensional model in the electronic memory.

Imaging software would allow the three-dimensional model of thepatient's anatomy obtained using the steerable endoscope 100 to beviewed on a computer monitor or the like. This would facilitatecomparisons between the three-dimensional model and images obtained withother imaging modalities, for example fluoroscopy, radiography,ultrasonography, magnetic resonance imaging (MRI), computed tomography(CT scan), electron beam tomography or virtual colonoscopy. Conversely,images from these other imaging modalities can be used to map out anapproximate path or trajectory to facilitate insertion of the endoscopebody 102. In addition, images from other imaging modalities can be usedto facilitate locating suspected lesions with the steerable endoscope100. For example, images obtained using a barium-contrast radiograph ofthe colon can be used to map out an approximate path to facilitateinsertion of the endoscope body 102 into the patient's colon. Thelocation and depth of any suspected lesions seen on the radiograph canbe noted so that the endoscope body 102 can be quickly and reliablyguided to the vicinity of the lesion.

Imaging modalities that provide three-dimensional information, such asbiplanar fluoroscopy, CT or MRI, can be used to program the electronicmotion controller 140 so that the endoscope body 102 will automaticallyassume the proper shape to follow the desired path as it is advancedthrough the patient's anatomy. In embodiments of the steerable endoscope100 that are configured for automatically advancing and withdrawing theendoscope body 102, the endoscope body 102 can be commanded to advanceautomatically though the patient's anatomy along the desired path asdetermined by the three-dimensional imaging information. Similarly, theendoscope body 102 can be commanded to advance automatically to the siteof a suspected lesion or other point of interest noted on the images.

As described above, the axial motion transducer 150 can be made in manypossible configurations, e.g., shown in FIG. 2 as a ring 152. Itfunctions partially as a fixed point of reference or datum to produce asignal indicative of the axial position of the endoscope body 102 withrespect to the fixed point of reference. The axial motion transducer 150may use optical, electronic or mechanical methods to measure the axialposition of the endoscope body 102. One preferable embodiment of thedatum 234 is shown schematically in FIGS. 18-20 as an instrumentedspeculum which may be placed partially into the rectum of the patient orat least adjacent to the anus A of a patient. Prior to the segmentedendoscopic body 238 being inserted into the anus A, it is preferablyfirst passed through the datum channel 236 of datum 234. The datum 234may house the electronics and mechanical assemblies necessary to measurethe depth of insertion, as discussed below, and it may also provide afixed, solid base to aid in co-locating the endoscopic body 238 adjacentto the anus A or body orifice as well as provide a base to stabilize andinsert the endoscope body 238 into the orifice. The instrumentedspeculum may be constructed of a biocompatible material, such asinjection-molded plastic, and house inexpensive electronics, as thespeculum may preferably be disposable.

As the endoscopic body 238 passes through the datum channel 236, onepreferable optical method of measuring the depth of insertion and axialposition may involve measurement through the use of reflective infra-redsensors mounted on the datum 234. The outer surface of the endoscopicbody 238 may have hatch marks or some other indicative or reflectivemarking placed at known intervals along the body 238. As the endoscopicbody 238 is advanced or withdrawn through the anus A and the datumchannel 236, an optical sensor can read or sense the hatch marks andincrement or decrement the distance traveled by the endoscopic bodyaccordingly. Thus, a sensor reading such marks may have an output thatregisters as a logic-level “1” or “ON” when a mark is sensed and alogic-level “0” or “OFF” when no mark is sensed. By counting or trackingthe number of 1-to-0 transitions on a sensor output, the depth may bemeasured accordingly. Thus resolution of the depth measurement may bedetermined in part in this embodiment by the spacing between the hatchmarks.

A simplified representation of how the distance may be used to advancethe device may be seen in FIG. 18. The endoscopic body 238 is advanceduntil the distal tip reaches a depth of L₁, as measured from themidpoint of the datum speculum 234. At this depth, it is necessary forthe user to selectively steer the tip to follow the sigmoid colon S suchthat the body forms a radius of curvature R₁. Once the position anddepth of this feature has been defined by the distal tip, any proximalsegment that reaches this depth of L₁ can be commanded to configureitself in the same manner as the distal tip segment until it hasachieved the correct combination of bends to negotiate the turn. As thebody 238 is further advanced, as seen in FIG. 19, it will eventuallyreach the second major bend at a depth of L₁+L₂. Accordingly, as for L₁,any segment that is advanced and reaches a depth of L₁+L₂ will likewisebe commanded to execute a turn as defined by the distal tip beingselectively steered when it first passed the second bend into thedescending colon D. Again as the body 238 is further advanced, as shownin FIG. 20, any subsequent segment that is advanced to reach a depth ofL₁+L₂+L₃ will be commanded to execute and negotiate the turn to followthe transverse colon T, again where the original curve has been definedby the selectively steerable distal tip.

FIG. 21 shows a schematic of one embodiment of a control system whichmay be used to control and command the individual segments of asegmented endoscopic device of the type shown in FIGS. 8-11B. As seen, amaster controller 248, which preferably resides at a location away fromthe segmented endoscope 242, may be used to control and oversee thedepth measurement as the endoscope 242 is inserted 256 into a patient.The master controller 248 may also be used to manage and communicate theactuation efforts of each of the joints and segments 242 ₁ to 242 _(n)by remaining in electrical communication through communications channels252, which may include electrical wires, optical fibers, wirelesstransmission, etc. As also shown in this embodiment, the mastercontroller 248 may also be in communication with datum 244 via datumcommunication channel 254 to measure and track the depth of insertion ofthe endoscope 242 as it passes through datum channel 246, as describedabove.

The segmented embodiment 242 may be comprised of a number of individualsegments 242 ₁ to 242 _(n) (only segments 242, to 2425 are shown forclarity). Each segment 242 ₁ to 242 _(n) preferably has its own separatecontroller 250 ₁ to 250 _(n), respectively, contained within eachsegment. Types of controllers used may include microcontrollers. Thecontrollers 250 ₁ to 250 _(n) may serve to perform several functions,e.g., measuring the angle of each segment joint in each of the two axesα and β, as described above, activating the motors contained within thesegments 242 ₁ to 242 _(n) to actuate endoscope 242 movement, andreceiving and handling commands issued from the master controller 248.Having individual controllers 250 ₁ to 250 _(n) in each respectivesegment 242 ₁ to 242 _(n) enables each segment to manage therequirements for a given configuration locally at the controller levelwithout oversight from the master controller 248 after a command hasbeen issued.

Accordingly, a flow chart embodiment for the master controller algorithm260, as shown in FIG. 22, may be used to control the overall functionduring insertion into a patient. During an initial step 262, the overallsystem (such as that shown in FIG. 21) may be initialized where allposition sensors are zeroed. The master controller 248 then enters awaiting state where it continually monitors the depth measurementgathered by the datum 244 located proximally of body opening, as shownin step 264. Once movement, i.e., depth measurement, is detected by thedatum 244 in step 264, the master controller 248 then determines whetherthe direction of motion of the endoscopic body 242 is being advanced,i.e., inserted, or withdrawn. As shown in step 266, if the endoscopicbody 242 is being inserted and the depth is increasing, the currentdepth is incremented, as in step 268; otherwise, the current depth isdecremented, as in step 270. Once the depth has been determined, themaster controller 248 communicates to each segment 242 ₁ to 242 _(n)individually and commands each to actuate to adjust or correct itsposition relative to the adjacent segments for the current depth, asshown in step 272. Afterwards, the master controller 248 continues tomonitor any changes in depth and the process is repeated as shown.

To maintain the orientation of each axis α and β and the positioning andthe depth of each segment 242 ₁ to 242 _(n), a data array, or similardata structure, may be used by the master controller 248 to organize theinformation, as shown in the following Table 1. Depth index D₁ to D_(n)is used here to denote the individual hatch marks, as seen in FIG. 21,and the distance between the hatch marks is a known value. Thus, theresolution with which the endoscope 242 can maintain its shape maydepend at least in part upon the spacing between the depth indices D₁ toD_(n). Moreover, the number and spacing of the indices D₁ to D_(n) maybe determined and set according to the specific application andnecessary requirements. Additional smoothing algorithms may be used andimplemented to further create gradual transitions between segments 242 ₁to 242 _(n) or between discrete depth measurement indices D₁ to D_(n).

TABLE 1 Data array of individual segments. Segment 1 Segment 2 Segment NDepth Index α/β α/β . . . α/β D₁ α_(D1)/β_(D1) α_(D1)/β_(D1) . . .α_(D1)/β_(D1) D₂ α_(D2)/β_(D2) α_(D2)/β_(D2) . . . α_(D2)/β_(D2) D₃α_(D3)/β_(D3) α_(D3)/β_(D3) . . . α_(D3)/β_(D3) . . . . . . . . . . . .. . . D_(n) α_(Dn)/β_(Dn) α_(Dn)/β_(Dn) . . . α_(Dn)/β_(Dn)

FIG. 23 shows a flowchart embodiment of the segment controller algorithm280. While the master controller 248 manages the measurement of theoverall depth of insertion of the endoscope 242 and determines theoverall shape, it may also communicate with the individual controllers250 ₁ to 250 _(n) in each segment 242 ₁ to 242 _(n), respectively, sothat the computation task of managing the motion of the entire system ispreferably distributed.

As discussed above, the individual controllers 250 ₁ to 250 _(n) mayserve a variety of functions, including accepting commands from themaster controller 248, managing communications with other controllers asnecessary, measuring and controlling the position of individual segments242 ₁ to 242 _(n), and performing diagnostics, error checking, etc.,among other things. The algorithm to control each segment 242 ₁ to 242_(n) is preferably similar for each segment; although the lead segment242 ₁ or first few segments are under the guidance of the physician toselectively control and steer so that the desired curve is set for anappropriate path to be followed

The initial step 282 for the system preferably first occurs where allcommunications, actuator (or motor), position sensors, and orientationare initialized. The controllers 250 ₁ to 250 _(n) may then wait toreceive any communications from the master controller 248 in step 284.If no communications are received, the controllers 250 ₁ to 250 _(n)preferably enter into a main loop while awaiting commands. When acommand is received, each of the controllers 250 ₁ to 250 _(n) mayrequest diagnostic data, as in step 286. If diagnostic data isrequested, the appropriate diagnostics are performed in step 288 and theresults are sent back to the master controller 248, as in step 290. Ifno diagnostic data is requested in step 286, each of the controllers 250₁ to 250 _(n) in step 292 may then determine whether actuation or motionhas been requested by the master controller 248. If no actuation ormotion has been requested, the relevant segment may continue to receivea command; otherwise, the relevant segment determines whether a commandhas been issued affecting the segment axis α, as in step 294, or segmentaxis β, as in step 300. If the segment axis α is to be altered, thecommand is sent to the α axis PID controller (or to a superior controlscheme) in step 296, and the appropriate actuator is subsequentlyactivated effecting the actuation of the segment in the α axis, as instep 298. Likewise, if the segment axis β is to be altered, either aloneor in conjunction with the α axis, the command is sent to the β axis PIDcontroller (or to a superior control scheme) in step 302, and theappropriate actuator is subsequently activated effecting the actuationof the segment in the β axis, as shown in step 304. Once the appropriatecommands have been effectuated, the controllers 250 ₁ to 250 _(n) againenter the main loop to await any further commands.

Although the endoscope of the present invention has been described foruse as a colonoscope, the endoscope can be configured for a number ofother medical and industrial applications. In addition, the presentinvention can also be configured as a catheter, cannula, surgicalinstrument or introducer sheath that uses the principles of theinvention for navigating through tortuous body channels.

In a variation of the method that is particularly applicable tolaparoscopy or thoracoscopy procedures, the steerable endoscope 100 canbe selectively maneuvered along a desired path around and between organsin a patient's body cavity. The distal end 108 of the endoscope 100 isinserted into the patient's body cavity through a natural opening,through a surgical incision or through a surgical cannula, introducer,or trocar. The selectively steerable distal portion 104 can be used toexplore and examine the patient's body cavity and to select a patharound and between the patient's organs. The electronic motioncontroller 140 can be used to control the automatically controlledproximal portion 106 of the endoscope body 102 to follow the selectedpath and, if necessary, to return to a desired location using thethree-dimensional model in the electronic memory of the electronicmotion controller 140.

A further variation which involves a non-contact method of measurementand tracking of the steerable endoscope is seen in FIGS. 24 to 26. Thisvariation may be used in conjunction with sensor-based systems ortransponders, e.g., coils or magnetic sensors, for tracking of theendoscope via magnetic detection technology or a navigational system ordevice external to the patient employing a scheme similar to that usedin global positioning systems (GPS). Magnetic sensors may be used, butcoils are preferable because of their ability to resonate at distinctfrequencies as well as their ability to have a unique “signature”, whichmay allow for the use of several different coils to be usedsimultaneously. Seen in FIG. 24, the endoscopic body 238 may be insertedinto a patient via the anus A. Located on the endoscope body 238 aretransponders 310 to 318 which may be placed at predetermined positionssuch as the selectively steerable distal tip.

As the endoscope 238 is advanced through the descending D and transversecolon T, the transponders may be detected by an external navigationalunit 320 which may have a display 322 showing the position of theendoscope 238 within the patient. As the endoscope 238 is furtheradvanced within the patient, as seen in FIG. 26, the navigational unit320 may accordingly show the corresponding movement. The use of anavigational unit 320 presents a non-contact method of navigating adevice such as the endoscope 238 and may be used to measure and locatedifferent positions within the patient relative to anatomical landmarks,such as the anus A or ileocecal valve. Furthermore, such an embodimentmay be used either alone or in conjunction with the datum speculum 234instrumentation as described above.

Use of the navigational unit 320 may also be particularly applicable tolaparoscopy or thoracoscopy procedures, as described above, in spaceswithin the body other than the colon. For example, the endoscope 238 mayalso be selectively maneuvered along a desired path around and betweenorgans in a patient's body cavity through any of the openings into thebody discussed above. While being maneuvered through the body cavity,the endoscope 238 may be guided and tracked by the externally locatednavigational unit 320 while the endoscope's 238 location may beelectronically marked and noted relative to a predetermined referencepoint, such as the datum, or relative to anatomical landmarks, asdescribed above.

While the present invention has been described herein with respect tothe exemplary embodiments and the best mode for practicing theinvention, it will be apparent to one of ordinary skill in the art thatmany modifications, improvements and subcombinations of the variousembodiments, adaptations and variations can be made to the inventionwithout departing from the spirit and scope thereof.

1-10. (canceled)
 11. A method for determining the three dimensionalshape of an instrument during or after insertion of said instrument intoa body cavity, wherein said instrument comprises an elongate bodycomprising a selectively steerable distal tip, and a plurality ofautomatically controlled segments proximal to said selectively steerabledistal tip, said method comprising: advancing said instrument into saidbody cavity; providing axial position data to a controller, wherein saidaxial position data is relative to a datum; providing angular positiondata to said controller from a respective segment controller associatedwith each of said plurality of automatically controlled segments; andgenerating in electronic memory of said controller a three-dimensionalmodel of a shape of said instrument using the provided axial positiondata and the angular position data.
 12. The method for determining thethree dimensional shape of an instrument according to claim 11, whereinthe providing angular position data further comprises: providing angularposition data to said controller from each segment controller using anoptical fiber communications channel between said controller and eachsegment controller.
 13. The method for determining the three dimensionalshape of an instrument according to claim 11, wherein the providingangular position data further comprises: providing angular position datato said controller from each segment controller using an electricallyconductive communication channel between said controller and eachsegment controller.
 14. The method for determining the three dimensionalshape of an instrument according to claim 11, wherein the providingangular position data further comprises: wirelessly providing angularposition data to said controller from each segment.
 15. A system fordetermining the shape of a surgical instrument, comprising: an elongateinstrument body comprising a selectively steerable distal tip, a pair ofautomatically controlled segments proximal to the selectively steerabledistal tip, and a joint that couples the pair of adjacent automaticallycontrolled segments together; an actuator associated with the joint,wherein the actuator changes an angle of the joint; a position encoderthat provides information associated with the angle of the joint,wherein the position encoder is positioned along the instrument body;and a controller coupled to receive the information associated with theangle of the joint and coupled to generate and transmit movement controlcommands to the actuator; wherein the controller generates a threedimensional model of a shape of the instrument with the informationassociated with the angle of the joint.
 16. The system of claim 15:wherein the joint comprises at least two degrees of freedom.
 17. Thesystem of claim 15 further comprising: a second actuator associated withthe joint; wherein the controller is coupled to generate second movementcontrol commands to the second actuator; wherein the actuator changesthe angle of joint in a first degree of freedom of the joint; andwherein the second actuator changes the angle of the joint in a seconddegree of freedom of the joint.
 18. The system of claim 15: wherein theactuator comprises a motor, and wherein the position encoder tracksangular rotational motion of a shaft of the motor.
 19. The system ofclaim 15: wherein the actuator is positioned along the instrument body.20. The system of claim 15 further comprising: an axial motiontransducer that provides axial position data of the elongate body;wherein the controller is coupled to receive the axial position data;and wherein the controller generates the three dimensional model of theshape of the instrument with the axial position data.
 21. The system ofclaim 15: wherein the elongate instrument body comprises a body portionof an endoscope.
 22. The system of claim 15: wherein if the angle of thejoint exceeds a predetermined acceptable range of angles, then thecontroller generates an alarm.
 23. The system of claim 15: wherein ifthe angle of the joint exceeds a predetermined acceptable range ofangles, then the controller generates a command to place theautomatically controlled segments in a neutral position.
 24. The methodof claim 11, further comprising the controller commanding each segmentcontroller to control the geometry of the segment with which eachsegment controller is associated during the advancing.
 25. The method ofclaim 11, further comprising the controller controlling an orientationof two independent axes between adjacent segments in the plurality ofautomatically controlled segments during the advancing.
 26. The methodof claim 11, further comprising displaying the three-dimensional modelon a display.
 27. The method of claim 11, further comprising combiningthe three-dimensional model with a three dimensional image of said bodycavity to form a combined three dimensional image.
 28. The method ofclaim 27, further comprising displaying corresponding movement of theinstrument within the body cavity based on the combined threedimensional image.
 29. The method of claim 11, further comprising thecontroller commanding each segment controller to control at least one ofthe motor and a second actuation in each segment of the plurality ofautomatically controlled segments, wherein the motor changes an angle ofa joint coupling a pair of the plurality of automatically controlledsegments in a first degree of freedom of the joint, wherein the secondactuator changes an angle of the joint in a second degree of freedom ofthe joint.
 30. The method of claim 11, wherein the providing the angularposition data further comprises determining angular rotational motion ofa shaft of the motor in each segment.
 31. The method of claim 11,further comprising the controller generating at least one of an alarmand a command to place the automatically controlled segments in aneutral position in response to an angle of a joint coupling a pair ofthe plurality of automatically controlled segments exceeding apredetermined acceptable range for the angle.